Ice accretion on the wings of fixed-wing and on the rotors of rotary-wing aircraft can have disastrous results. The ice that forms on a wing structure, especially along the leading edge, modifies the aerodynamics of the wing, resulting in decreased lift. In the extreme, this can lead to loss of lift and control of the aircraft and potentially a crash. Ice building up elsewhere on the wing and airframe can add significant weight to the aircraft. Several techniques and flight protocols have been developed and are widely used to prevent a plane from becoming ice-covered, both in flight and on the ground.
Some, typically larger, aircraft are equipped with in-flight heaters that melt the ice before it can substantially build up on wings or rotor blades. Protocols have been established for permitting or denying flight under weather conditions or into areas where the potential of aircraft icing is high. On the ground, there are deicing protocols and methods that ensure that there is little to no accretion of ice on wings or rotors immediately prior to flight.
An outstanding problem is that it is difficult while in flight or on the ground to determine when ice is building up on the aircraft until a substantial accretion has taken place. By that time, it may be difficult, or even too late to take evasive maneuvers or rely on the in-flight deicing capability.
On the ground, it would be useful to be able to monitor the state of wing and airframe coverage by deicing fluid, liquid water or the accretion of ice. Availability of this information could be used to decide when to implement deicing procedures with greater efficiency and economy.